DE1024708B - Process for the production of planar structures and molded articles from hardened modified epoxy resins - Google Patents

Description

GERMAN

Various curing agents have already been used for the production of sheet-like structures and moldings Epoxy resins described, the latter by condensation of polyhydric phenols, such as 2,2-bis- (4-oxyphenyl) propane, obtained with epihalohydrins or dihalohydrins in a preferably alkaline medium will. Such known hardening agents are, for example, aliphatic di- or polyamines or polyamides or polymeric carboxylic acid esters with some free acid groups. Addition products from epoxy resins and an excess of polyamines, which therefore have free amino groups, have already been described for curing purposes of this type.

If such epoxy resins cured in the usual way for the production of, for example, lacquer and paint coatings are used, they have various disadvantages. In particular, it is difficult to be equal Time a satisfactory resistance both to the action of water and to the action of solvents. For example, when using small amounts of ethylenediamine as a hardening agent, the water resistance is improved, but the resistance to solvents is not then left to be desired. The opposite is the case when using relatively large amounts of ethylenediamine.

In addition, when diamines and polyamines are used as hardeners, clouding occurs in the hardened Product observed, especially when the curing reaction is carried out in damp, cold weather. Another disadvantage of these hardeners lies in the poor flow properties of the end products give rise to an uneven formation of the surface.

It has now been found that the disadvantages outlined can be largely avoided if the concerned condensation products harden in two stages under the following conditions. In the first stage of the procedure is a condensate containing free epoxy groups in solution or in the molten state at least 50 ° reacted with an organic compound which has at least three active hydrogen atoms Nitrogen atoms of aromatic di- or higher-valent amines or in the form of alcoholic and phenolic hydroxyl groups and / or mercapto groups until one is still in organic solvents soluble, hardenable and viscosity-stable product is created. If at this stage a phenylenediamine is used as the organic compound, its amount should be at most 0.15 mol, based on the amount by weight of the epoxy resin, which is 1 gram equivalent contains a 1,2-epoxy group.

In the second process step, the resin is dissolved in an organic solvent with as

Method of manufacture

of flat structures and moldings

made of cured modified epoxy resins

Applicant:

NV De Bataafsche Petroleum
Maatschappij, The Hague

Representative: Dr. K. Schwarzhans, patent attorney,
Munich 19, Romanplatz 9

Claimed priority:
Netherlands from January 15, 1954

Pieter Bruin and Hendricus Anthonius Oosterhof,

Amsterdam, Netherlands),
have been named as inventors

Epoxy resin curing agents mixed compounds known per se and cured after molding. Suitable organic compounds for use in the first process stage are phenylenediamines, ζ. B. m-phenylenediamine, or a phenol-formaldehyde resin with two phenolic hydroxyl groups and at least a methylol group.

One possible explanation for the novel effect achieved in the first procedural stage is that that the organic compounds mentioned come into reaction with the epoxy resins, but without reference the polymerization, which could occur through reaction of the epoxy groups, to act as a catalyst.

Since the active hydrogen atoms of the organic compound are practically all by the end of the first stage have reacted, the resulting reaction product is stable, i. i.e., it remains soluble even if it is for long periods of time Time is stored. However, if ethylenediamine or diethylenetriamine, which are both condensing and catalytic Have an effect, for example, were used for the reaction described, that would be obtained Product not stable as the reaction would continue due to the catalytic effectiveness.

Due to the presence of at least three active hydrogen atoms in the described organic Compounds, the soluble reaction product has a Spatially networked structure, in complete contrast to the chain structure that occurs when using organic Compounds with only two active hydrogen atoms is obtained.

709 880/435

3 4

In the second process stage, components are preferably used, such as pigments, color aliphatics Di- or polyamines, such as ethylenediamine, substances, plasticizers, fillers and other resins or Diethylenetriamine, or addition compounds of such resin-forming material.

Amines used with epoxy resins as curing agents. In the following examples, parts are parts by weight and

These compounds are percentages by weight even at ordinary temperatures. That as a starting point effective, although also higher temperatures up to the material used epoxy resin on which the examples 250 ° can be used, whereby the hardening reference was made from bisphenol (2,2-bis- (4-oxyreaction is accelerated. Preferably this is phenyl) propane) and epichlorohydrin in an alkaline second stage, however, produced at temperatures between 10 and medium. 40 ° carried out. io Beismel I

It has been found that in the ^F

Procedure in the second process stage a smaller 2 parts of m-phenylenediamine per 100 parts of condensate

Amount of curing agent is required than was previously possible for a 60 "/" strength viscous solution of an epoxy was. For example, if the epoxy resin is first added to toluene, which has a medium molecular weight 1 and 2 percent by weight of m-phenylenediamine by weight of 900, a softening point of 71 ° and was sufficient for the curing reaction in which showed an epoxy equivalent weight of 481. The Mizweits Stage 2.5 or 1.5 percent by weight of ethylene solution was heated to 120 to 125 ° and 2 hours below diamine. In the case of a one-step procedure, however, the stirring was kept at this temperature. After cooling down At least 3.5 percent by weight of the complete hardener solution was made with a mixture of the same processing necessary when ethylenediamine is used as hardener 20 parts of methyl isobutyl ketone, monoethyl ether of ethyl became. Lenglycol and toluene diluted to a viscosity, at

This reduction in the amount of curing agent which it could be sprayed, The ethylene diamine used is of great importance. 1.5 parts of ethylene were added to the diluted solution the water resistance of the end product, such as one diamine, given for every 100 parts of the reaction product has already been explained at the beginning. In general it is possible to degrease the mixture with a sandblast and it is preferable that the steel plates of 1 mm thickness which have been blown in the second process stage are used To use hardening agent in an amount, sprays. The films obtained were at for 1 week which 0.2 equivalents of active hydrogen atoms hardened 23 ° and then tested.

not per 100 g of the reaction product to be hardened. The so-called pencil hardness was good and was 4 H;

exceeds. 30 d. that is, the film became a scratch when the tip was scratched

The 4 H hardness pencil produced according to the new process was not damaged. The bending hardened Coatings had a pleasing uniformity that was excellent (determined by bending over Appearance, and the formation of opacities could be achieved with a thorn of 3.125 mm) and it was also beaten chosen conditions in terms of type and quantity strength good. The latter was made with a 910-g Gedes hardening agent used can be prevented. 35 weight with a spherical end of 9 mm radius be-Die Production of the still soluble, viscosity-stable correct, which from a height of 105 cm on the back resin In the first stage of the process, for example, the side of the steel sheets is dropped, carried out in solution. The solvent resistance was also important for this purpose.

Epoxy-containing condensation product and the drawn, it was determined by viewing the film organic compound with at least three active 4 ° in contact with methyl isobutyl ketone for 1 hour at 23 ° Hydrogen atoms dissolved in toluene. This solution is brought. The film could afterwards with a pencil at least 50 °, preferably 120 to 200 °, as long as the hardness F is not scratched, heated until practically all active hydrogen atoms. The water resistance of the film was found to react in the same way have what can be recognized by the fact that when if as well, because it remained unchanged when it was 1 hour further heating practically no increase in viscosity 45 was brought into contact with boiling water, of the conversion product takes place more. In place after 4 hours, under the same conditions toluene or xylene can also contain ketones, such as methyl only very small needle-like bubbles ethyl ketone, can be used as a solvent. will.

Very good coatings are found, for example, under the The film also showed excellent resistance to the following Conditions received. 50 about solutions of caustic alkalis, what happens in a

The condensation product is in a suitable 10 hour treatment with boiling (112 °) 20% Solvent, such as xylene, dissolved and at about 120 to solution of sodium hydroxide showed of which he 200 ° was not attacked, for example with 2 percent by weight of m-phenylene.

diamine condensed. The reaction product thus obtained. When sprayed, the flow properties were shown

is far better with a solvent or mixture of 55 than with a one-step cure with Diluted solvents and after adding a hardening ethylenediamine.

The haze in the films was even at low levels

Solution, applied as a coating. Extraordinary after a further temperature and high humidity Hardening for about a week at 20 ° (if necessary slight.

agile for about 3 days at 40 °) the coating is given 60 Beismel II

the optimal properties.

The 10 parts of a phenol-formaldehyde resin to be used in the second process stage with a medium

Curing agent, for example ethylenediamine, is added to a lere number of 6 phenolic O H groups, 4.2 methyl olers obtained in the first stage stable soluble reac groups (CH ₂ OH) and 1.8 CH ₂ OC ₄ H ₉ groups per tion mixture given, whereupon the mixture, if necessary 65 molecules were added to 100 parts of a condensate, maneuverable immediately, applied in the form of a coating. This was in the form of an 80% viscous solution, so that the hardening of the second process xylene before, the epoxy step described in Example I taking place entirely in the coating itself. resin was used. The solution was at a

In the production according to the invention of surface temperature of 120 to 130 ° produced, whereupon the Formed and molded bodies can also be a number of further 70 mixtures heated for 1 hour with stirring to 165 to 170 °

became. After cooling, the solution was adjusted to a viscosity suitable for spraying in that described in Example I. Kind of diluted. To the thus diluted solution was 2.5 parts of ethylenediamine per 100 parts of the formed Given the reaction product and then sprayed the mixture. The obtained film was like described in Example I, cured and tested.

Pencil hardness, flexibility, impact resistance, resilience against solvents and caustic alkali solutions were extremely satisfactory, accurate as in example I.

The water resistance was better than in Example I, since even after 4 hours of contact with boiling Water practically no damage was observed.

Example III

For comparison purposes, a film was made from a previously unreacted epoxy resin and tested.

For this purpose, a solution was brought to a viscosity suitable for spraying at room temperature, by the starting material described in Example I in a mixture of 45 parts of methyl isobutyl ketone, 5 parts of monobutyl butyl ether of ethylene glycol and 50 parts of toluene dissolved. It became one Amount of a 50% solution of ethylenediamine in a Mixture of equal parts of butanol and toluene added to this solution that the mixture to be sprayed Contained 4 parts of ethylenediamine per 100 parts of ethoxylin resin.

The solution was sprayed at 23 ° and the film obtained was cured in the manner described in Example I. The flow properties during spraying were very poor, so that the film obtained had craters and pores exhibited. The pencil hardness was 3 H. The flexibility, impact resistance and resistance to solvents and caustic alkalis were good. However, the water resistance was very poor due to blistering the film appeared after 15 minutes of contact with boiling water. When the humidity is relatively high considerable cloudiness appeared at 15 °.

Example IV

I ¹ Iz parts of m-phenylenediamine per 100 parts of condensate was added to a 80 ° / o viscous solution of the epoxy resin described in Example I in xylene. The solution was prepared at a temperature between 120 and 130 ° and kept with stirring for 3 hours at a temperature between 120 and 125 °. After cooling, the solution was diluted with a mixture of equal parts of methyl isobutyl ketone, monoethyl ether of ethylene glycol and toluene.

22 parts of an addition compound of ethylenediamine with the epoxide groups initial condensation product (corresponding to 2 parts of ethylene diamine) were added to the thus diluted solution as a 50 ° / ₀ by weight solution in a mixture of equal parts of n-butanol and toluene. The whole was then diluted with a solution of equal parts of methyl isobutyl ketone, glycol monoethyl ether and toluene in order to obtain a viscosity suitable for spraying.

The above addition compound was obtained by adding 1000 g of the epoxy resin described in Example I. with stirring in a solution of 400 g of ethylenediamine in 1000 g of a mixture of equal parts secondary butanol and xylene. As a result of the heat given off during the reaction, the Temperature to about 40 °. After about 3 hours of stirring, the starting material was completely dissolved and the Solvent and excess ethylenediamine were removed by distillation. To remove the last Residual volatile substances, the bubble temperature of the distillation vessel was increased to 150 °, whereby a Vacuum of 2 mm of mercury was applied.

The melting point of the addition compound (Durrans mercury method) was about 90 °, while the Nitrogen content was 5 weight percent. The theoretical nitrogen content of the addition compound is

5.18%

The flow properties of the mixture of the addition product described and the reaction product from the first process stage during the Spraying was considerably better than if the epoxy resin to be cured had not been modified beforehand were. After curing, the film did not show any defects. Even at a very low temperature and a high one Moisture did not show any turbidity.

Pencil hardness, flexibility, impact resistance and resistance to solvents and caustic alkali solutions were very satisfactory, as in example I.

The water resistance corresponded approximately to that given in Example I.

Claims (5)

Patent claims? 1. Process for the production of sheet-like structures and moldings from hardened, modified epoxy resins, characterized in that a condensation product of polyhydric phenols and epihalohydrins or dihalohydrins having at least three active hydrogen atoms on nitrogen atoms of aromatic di- or higher-valent amines or in alcoholic and phenolic Hydroxyl groups and / or organic compounds containing mercapto groups in at least 50 ° converted into a curable, viscosity-stable resin that is still soluble in organic solvents is, in the case of using m-phenylenediamine this compound in an amount of at most 0.15 mol based on the amount by weight of the epoxy resin which is one gram equivalent contains a 1,2-epoxy group, and that then the resin after dissolving in an organic Solvent and addition of compounds known per se as epoxy resin curing agents is hardened after shaping. 2. The method according to claim 1, characterized in that the organic compound with active Hydrogen atoms m-phenylenediamine in an amount of at least 2% based on the weight of the Condensation product, is used. 3. The method according to claim 1 or 2, characterized in that the reaction of the condensation product with the active hydrogen atoms Connection is carried out at a temperature between 120 and 200 °. 4. The method according to claim 1 to 3, characterized in that the curing agent in a maximum amount of 0.20 equivalents of active hydrogen atoms per 100 grams of the curable resin is used will. 5. The method according to claim 1 to 4, characterized in that the curing at temperatures between 10 and 40 ° carried out wild. Documents considered: French Patent Nos. 881 981, 96 044; U.S. Patent Nos. 2,589,245, 2,651,589. Cited earlier rights: German Patent No. 959 137. © 709 880/435 2.58